1. Field of Invention
The invention relates to a feeder of short rods for a machine tool such as a turning lathe or an automobile lathe, comprising a rod loading device having a plurality of retention elements, arranged in parallel and aligned to one another, for holding a plurality of rods placed on an inclined plane, and loading slides, a device for centering rods according to an axis of alignment with respect to the machine tool, and a device for advancing rods in the said machine tool.
2. Description of the Related Art
The object of these feeders is to feed rods automatically, in particular to automatic lathes, which makes it possible to improve appreciably the production of these machines and reduce considerably the costs of the pieces machined on the machine tool. The term "rod" as used in the present patent application includes prismatic oblong pieces of any material, including tubes, whose length considerably exceeds their diameter.
The known feeders and their functioning will now be described in detail below. In general, the feeders comprise a frame on which is mounted a rod magazine in the form of an inclined plane, a loader which takes a rod to be machined from the magazine, centers it horizontally, and lifts it, a vertical centering device to align the rod coaxially with the spindle of the associated lathe, and an advancement device to push the rod into the spindle.
The known feeders have several drawbacks, however. First of all--and this drawback is the most serious one--the loading operation is carried out in a rough manner since the device is subjected to two successive impacts during the loading procedure: the first impact is caused when a rod to be loaded, held in the magazine by a parallel series of retention fingers, falls into the loader during an ascending movement thereof which is necessary in order to transport the rod from a lower level, that of the magazine, to the level of the shaft of the spindle This jolt is particularly violent and loud, and can damage certain parts of the feeder. To give an indication, the weight of a single rod of steel with a diameter of 80 mm and a length of 1200 mm is about 47 kg; these impacts can cause in the long run a misalignment between the feeder and the stockhead of the machine tool, bringing with it serious risks both for the feeder and for the machine tool.
The second impact is caused when a rod has been taken from the magazine and carried away by the loader, the next rod, being placed on the inclined plane of the magazine, is then going to knock against the said retention fingers. Although this impact is not dangerous for the feeder, it is not less disagreeable, and it produces vibrations which threaten to misalign the feeder with respect to the machine tool.